1. Field of the Invention
The present invention relates to a method for the treatment of metal strip, particularly for the treatment of hot-rolled metal strip in the entry portion of a pickling line through which the metal strip travels continuously. The method includes straightening the metal strip which is being uncoiled from an uncoiling reel under a predetermined strip tension, subsequently severing the unstraightened ends of the strip for producing straightened ends of the strip, and subsequently connecting the strip end of an advancing metal strip to the strip end of a subsequent metal strip.
The present invention further relates to an arrangement for carrying out the above-described method.
2. Description of the Related Art
It is known in the art to place in the entry portion of a pickling line the metal strip from an uncoiling reel over a guide roller onto the intended pass line and to supply the metal strip to a shearing machine over drivers and a prestraightening machine and finally to supply the strip to a connecting unit, for example, a welding machine. In the welding machine, the end of an advancing metal strip is connected by means of welding to the end of a subsequent metal strip. It is the purpose of the prestraightening machine to straighten the metal strip in the pass line after it had been introduced into the pass line.
However, the prestraightening machine can reduce waviness of the strip only to a small extent. The prestraightening machine has no influence on saber-shaped strip portions. In addition, it is not possible to produce high strip tensions in the prestraightening machine, for example, by high braking tensions at the uncoiling reel. This is because particularly hot-rolled coils are not sufficiently tightly coiled because of the waviness of the strip.
In order to eliminate strip waviness, such as, border undulations, trough-shaped strip portions or the like and to reduce or eliminate saber-shaped strip portions or horizontal curvatures, it is known in the art to cause the connected metal strips to travel after welding through a stretch-bending unit. However, an entry portion of the above-described type has the disadvantage that the metal strips in the welding machine are still wavy and still have trough-shaped strip portions which are particularly pronounced at the strip ends. Therefore, it is not possible to exactly center the strip ends to be connected. Rather, the strip ends are welded to each other more or less in inclined relative positions. In fact, wavy metal strips are upset in the welding clamps and are not welded with the full cross-section. Accordingly, the strip connection can tear totally or partially in the subsequent stretch-bending machine.
Another problem is the fact that wavy metal strips produce substantial noise when they travel through the treatment or pickling line, i.e., when traveling around the rollers, such as guide rollers, straightening rollers, drive rollers, tensioning rollers, etc.